No blimps have done this. The fleet might see no need for them to go out for long periods. However, the possibility has been established, and might be useful in the emergencies of war, or accident. While the primary usefulness of the blimp lies in the coastal waters, it can go to sea if needed--and stay out--can be used in convoy work or as a listening post.
Other improvements were uncovered during the experiments. A sea anchor or drogue was devised to enable the airship to "lay to" for extended periods, without consuming fuel, in case it wishes to use its listening devices against submarines, make repairs or for other purposes. Plans have been worked out for landing on the water in quiet bays in calm weather, utilizing flotation gear, or a three-point mooring to ordinary mud anchors--facilitating servicing from nearby Coast Guard stations.
Perhaps a significant thing about these experiments is that the principles seem applicable as well to rigid airships. The ability to pick up ballast in flight may well eliminate the necessity for ballast-recovery devices, with a substantial saving in cost, and an impressive saving in weight.
By eliminating the heavy condensers, and translating that weight-saving into fuel, it is estimated that the range of a ship of the Los Angeles size could be increased by 20 percent and ships of the Akron-Macon size by 15 percent, in the last case amounting to 1,250 miles of additional cruising radius.
A trans-oceanic passenger airship could start out with virtually no water ballast at all except a minimum amount for maneuvering, use its fuel supply as ballast and pick up sea water as needed. This could be done at 500 feet elevation, at the rate of 80 gallons a minute, using a 30 horsepower motor, could be done in half an hour a day. The ship need not slow down materially while doing this.
Application of this principle to military airships of the rigid type might be still more significant. The chief use for the rigid airship in war would seem to be as a high speed airplane carrier, whose planes would increase many fold its own reconnaissance range, and would be expected also to do the major part of what fighting became necessary in case of enemy contact. The airship itself in that situation would put more dependence on its speed of retreat and its ability to seek cover in clouds as the submarine does beneath the surface, than on its own machine guns and cannons.